- Base-Mediated Borylsilylation/Silylation of Ammonium Salts with Silylborane
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This work describes a base-mediated borylsilylation of benzylic ammonium salts to synthesize geminal silylboronates bearing benzylic proton under mild reaction conditions. Deaminative silylation of aryl ammonium salts was also achieved in the presence of
- Du, Xian,Guan, Yun-Shi,Li, Yi-Hui,Liang, Guohai,Luo, Yong,Qi, Wan-Ying,Wang, Zi-Ying,Wei, Xun,Xu, Xiao-Hong,Yuan, Han,Zhen, Jing-Song
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supporting information
p. 5988 - 5992
(2021/08/31)
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- A nickel-catalyzed silylation reaction of alkyl aryl sulfoxides with silylzinc reagents
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Ni(PEt3)Cl2-catalyzed silylation of alkyl aryl sulfoxides with silylzinc reagents was carried out. This protocol allows alkyl aryl sulfoxides to convert to arylsilicon compounds under mild reaction conditions, tolerates a range of functional groups and is suitable for a wide scope of substrates.
- Li, Wei-Ze,Wang, Zhong-Xia
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supporting information
p. 5082 - 5086
(2021/06/21)
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- Continuous-flow Si-H functionalizations of hydrosilanesviasequential organolithium reactions catalyzed by potassiumtert-butoxide
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We herein report an atom-economic flow approach to the selective and sequential mono-, di-, and tri-functionalizations of unactivated hydrosilanesviaserial organolithium reactions catalyzed by earth-abundant metal compounds. Based on the screening of various additives, we found that catalytic potassiumtert-butoxide (t-BuOK) facilitates the rapid reaction of organolithiums with hydrosilanes. Using a flow microreactor system, various organolithiums bearing functional groups were efficiently generatedin situunder mild conditions and consecutively reacted with hydrosilanes in the presence oft-BuOK within 1 min. We also successfully conducted the di-funtionalizations of dihydrosilane by sequential organolithium reactions, extending to a gram-scale-synthesis. Finally, the combinatorial functionalizations of trihydrosilane were achieved to give every conceivable combination of tetrasubstituted organosilane libraries based on a precise reaction control using an integrated one-flow system.
- Lee, Hyune-Jea,Kwak, Changmo,Kim, Dong-Pyo,Kim, Heejin
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supporting information
p. 1193 - 1199
(2021/02/26)
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- Hydrogenolysis of Polysilanes Catalyzed by Low-Valent Nickel Complexes
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The dehydrogenation of organosilanes (RxSiH4?x) under the formation of Si?Si bonds is an intensively investigated process leading to oligo- or polysilanes. The reverse reaction is little studied. To date, the hydrogenolysis of Si?Si bonds requires very harsh conditions and is very unselective, leading to multiple side products. Herein, we describe a new catalytic hydrogenation of oligo- and polysilanes that is highly selective and proceeds under mild conditions. New low-valent nickel hydride complexes are used as catalysts and secondary silanes, RR′SiH2, are obtained as products in high purity.
- Comas-Vives, Aleix,Eiler, Frederik,Grützmacher, Hansj?rg,Pribanic, Bruno,Trincado, Monica,Vogt, Matthias
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supporting information
p. 15603 - 15609
(2020/04/29)
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- METHOD FOR PRODUCING ARYLSILANE COMPOUND CONTAINING HALOSILANE COMPOUND AS RAW MATERIAL
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PROBLEM TO BE SOLVED: To provide a method for producing an arylsilane compound with low production cost. SOLUTION: A method for producing an arylsilane compound includes a reaction step for the cross-coupling reaction of a halosilane compound represented by general formula (A-1), (A-2), or (A-3) and an arylboronic acid pinacol ester in the presence of a nickel catalyst, a Lewis acid catalyst, and an organic base (R independently represent an aromatic hydrocarbon group, a heteroaromatic ring group, or a C1-20 hydrocarbon group; X independently represent a halogeno group or a trifluoromethanesulfonyloxy group). SELECTED DRAWING: None COPYRIGHT: (C)2020,JPOandINPIT
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-
Paragraph 0087-0091
(2020/03/06)
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- Nickel-Catalyzed Decarbonylation of Acylsilanes
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Nickel-catalyzed decarbonylation of acylsilanes is developed. In sharp contrast to cross-coupling reactions of acylsilanes, in which the silyl group serves as a leaving group, the silyl group is retained in the product in this decarbonylation reaction. Although the strong binding of the dissociated CO to the nickel center frequently hinders catalyst turnover in nickel-mediated decarbonylative reactions, this reaction can be catalyzed by nickel complexes bearing a CO ligand.
- Ito, Yuri,Kodama, Takuya,Nakatani, Syun,Sakurai, Shun,Tobisu, Mamoru
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p. 7588 - 7594
(2020/06/27)
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- Nickel-Catalyzed Reaction of Aryl 2-Pyridyl Ethers with Silylzinc Chlorides: Silylation of Aryl 2-Pyridyl Ethers via Cleavage of the Carbon?Oxygen Bond
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Ni-catalyzed C?O(Py) bond activation and silylation of aryl 2-pyridyl ethers with silylzinc chlorides were carried out. This protocol allowed the 2-pyridyloxy group to be substituted by a silyl group with short reaction times, mild reaction conditions, and good compatibility of functional groups. (Figure presented.).
- Kong, Ying-Ying,Wang, Zhong-Xia
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p. 5440 - 5448
(2019/11/16)
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- Nickel-Catalyzed Synthesis of Silanes from Silyl Ketones
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An unprecedented nickel-catalyzed decarbonylative silylation via CO extrusion intramolecular recombination fragment coupling of unstrained and nondirecting group-Assisted silyl ketones is described. The inexpensive and readily available catalyst performs
- Srimontree, Watchara,Lakornwong, Waranya,Rueping, Magnus
-
supporting information
p. 9330 - 9333
(2019/11/19)
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- Dimethylformamide-stabilised palladium nanoclusters catalysed coupling reactions of aryl halides with hydrosilanes/disilanes
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N,N-Dimethylformamide-stabilised Pd nanocluster (NC) catalysed cross-coupling reactions of hydrosilane/disilane have been investigated. In this reaction, the coupling reaction proceeds without ligands with low catalyst loading. N,N-Dimethylacetamide is a crucial solvent in these reactions. The solvent effect was considered by various techniques, such as transmission electron microscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis. The Pd NCs can be recycled five times under both hydrosilane and disilane reaction conditions.
- Nagata, Tatsuki,Inoue, Takeru,Lin, Xianjin,Ishimoto, Shinya,Nakamichi, Seiya,Oka, Hideo,Kondo, Ryota,Suzuki, Takeyuki,Obora, Yasushi
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p. 17425 - 17431
(2019/06/24)
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- In Situ Generation of Silyl Anion Species through Si?B Bond Activation for the Concerted Nucleophilic Aromatic Substitution of Fluoroarenes
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In situ generated silyl anion species enable the concerted nucleophilic aromatic substitution of fluoroarenes. Model DFT calculations indicated that addition of a base to a silylborane would thermodynamically form a silyl borate complex and then kinetically release a silyl anion species through Si?B bond cleavage, and that the in situ generated silyl anion equivalent would further react with a fluoroarene through a concerted nucleophilic aromatic substitution pathway with an activation barrier of ca. 20 kcal/mol to afford the silylated product with a large energy gain. Experiments confirmed that the defluorosilylation reaction took place smoothly at room temperature simply upon mixing fluoroarenes with commercially available silylborane and NaOtBu. Radical scavenger and radical clock reaction experiments provide further evidence for the in situ generation of the silyl anion.
- Kojima, Kumiko,Nagashima, Yuki,Wang, Chao,Uchiyama, Masanobu
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p. 277 - 280
(2019/04/04)
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- Silyldefluorination of Fluoroarenes by Concerted Nucleophilic Aromatic Substitution
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The reaction of readily generated silyl lithium reagents with various aryl fluorides to provide the corresponding aryl silanes is reported. DFT calculations reveal that the nucleophilic aromatic substitution of the fluoride anion by the silyl lithium reagent proceeds through concerted ipso substitution. In contrast to the classical nucleophilic aromatic substitution, this concerted ionic silyldefluorination also occurs on more electron-rich aryl fluorides.
- Mallick, Shubhadip,Xu, Pan,Würthwein, Ernst-Ulrich,Studer, Armido
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supporting information
p. 283 - 287
(2018/12/13)
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- METHOD FOR PREPARING SILAHYDROCARBONS
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The present disclosure is directed to a process for preparing silahydrocarbons of formula (I), the process comprising the step of reacting a compound of formula (II), with a compound of formula (III), as well as to silahydrocarbons prepared by such a process, and to compositions and articles of manufacture comprising such silahydrocarbons.
- -
-
Paragraph 120; 121; 154; 156; 190; 191
(2018/04/17)
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- A well-defined NHC-Ir(III) catalyst for the silylation of aromatic C-H bonds: Substrate survey and mechanistic insights
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A well-defined NHC-Ir(iii) catalyst, [Ir(H)2(IPr)(py)3][BF4] (IPr = 1,3-bis-(2,6-diisopropylphenyl)imidazol-2-ylidene), that provides access to a wide range of aryl- and heteroaryl-silanes by intermolecular dehydrogenative C-H bond silylation has been prepared and fully characterized. The directed and non-directed functionalisation of C-H bonds has been accomplished successfully using an arene as the limiting reagent and a variety of hydrosilanes in excess, including Et3SiH, Ph2MeSiH, PhMe2SiH, Ph3SiH and (EtO)3SiH. Examples that show unexpected selectivity patterns that stem from the presence of aromatic substituents in hydrosilanes are also presented. The selective bisarylation of bis(hydrosilane)s by directed or non-directed silylation of C-H bonds is also reported herein. Theoretical calculations at the DFT level shed light on the intermediate species in the catalytic cycle and the role played by the ligand system on the Ir(iii)/Ir(i) mechanism.
- Rubio-Pérez, Laura,Iglesias, Manuel,Munárriz, Julen,Polo, Victor,Passarelli, Vincenzo,Pérez-Torrente, Jesús J.,Oro, Luis A.
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p. 4811 - 4822
(2017/07/11)
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- Palladium-Catalyzed Cross-Coupling of Monochlorosilanes and Grignard Reagents
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Using a palladium catalyst supported by DrewPhos, the alkylation of monochlorosilanes with primary and secondary alkylmagnesium halides is now possible. Arylation with sterically demanding aromatic magnesium halides is also enabled. This transformation ov
- Vulovic, Bojan,Cinderella, Andrew P.,Watson, Donald A.
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p. 8113 - 8117
(2017/12/08)
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- Formal Nucleophilic Silyl Substitution of Aryl Halides with Silyllithium Reagents via Halogenophilic Attack of Silyl Nucleophiles
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A new reaction has been developed for the formal nucleophilic silyl substitution of aryl halides with silyllithium or silylpotassium reagents. Dimethylphenylsilyllithium reacted with various aryl halides to form the corresponding arylsilanes in moderate to good yields with concomitant formation of the disilanes under the optimized reaction conditions. Mechanistic studies indicated that this silyl substitution reaction progresses through polar halogenophilic attack of silyl nucleophiles.
- Yamamoto, Eiji,Ukigai, Satoshi,Ito, Hajime
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p. 2460 - 2464
(2017/10/06)
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- Selective Si?C(sp3) Bond Cleavage in (Aminomethyl)silanes by Carbanionic Nucleophiles and Its Stereochemical Course
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Selective cleavage of a silicon–carbon bond in tetraorganosilanes is still a great challenge. A new type of Si?C(sp3) bond cleavage in bench-stable (aminomethyl)silanes with common organolithium reagents as nucleophiles has now been identified. Suitable leaving groups are benzyl, allyl, and phenylthiomethyl groups. A β-donor function and polar solvents are essential for the reaction. Simple switching between α-deprotonation and substitution is possible through slight modifications of the reaction conditions. The stereochemical course of the reaction was elucidated by using a silicon-chiral benzylsilane. The new transformation proceeds stereospecifically with inversion of configuration and can be used for the targeted synthesis of enantiomerically pure tetraorganosilanes, which are otherwise difficult to access. Quantum chemical calculations provided insight into the mechanism of the new substitution.
- Koller, Stephan G.,Bauer, Jonathan O.,Strohmann, Carsten
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supporting information
p. 7991 - 7994
(2017/06/27)
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- Suzuki-type cross coupling between aryl halides and silylboranes for the syntheses of aryl silanes
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Herein we report Pd catalyzed Suzuki type cross coupling between aryl halides and silylboranes for the syntheses of aryl silanes. This reaction shows a general substrate scope, excellent compatibility with electrophilic functionalities and good yields.
- Guo, Huifang,Chen, Xiao,Zhao, Chunliang,He, Wei
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supporting information
p. 17410 - 17412
(2015/12/09)
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- Reaction mechanism of the anomalous formal nucleophilic borylation of organic halides with silylborane: Combined theoretical and experimental studies
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Theoretical and experimental studies have been conducted to elucidate the mechanism of the formal nucleophilic boryl substitution of aryl and alkyl bromides with silylborane in the presence of potassium methoxide. Density functional theory was used in conjunction with the artificial force induced reaction method in the current study to determine the mechanism of this reaction. The results of this analysis led to the identification of a unique carbanion-mediated mechanism involving the halogenophilic attack of a silyl nucleophile on the bromine atom of the substrate. These calculations have, therefore, provided a mechanistic rationale for this counterintuitive borylation reaction. Furthermore, the good functional group compatibility and high reactivity exhibited by this reaction toward sterically hindered substrates can be understood in terms of the low activation energy required for the reaction of the silyl nucleophile with the bromine atom of the substrate and the subsequent rapid and selective consumption of the carbanion species by the in situ generated boron electrophile. The results of an experimental study involving the capture of the anion intermediate provided further evidence in support of the generation of a carbanion species during the course of this reaction. The anomalous formal nucleophilic borylation mechanism reported in this study could be used to provide new insights into silicon and boron chemistry.
- Uematsu, Ryohei,Yamamoto, Eiji,Maeda, Satoshi,Ito, Hajime,Taketsugu, Tetsuya
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supporting information
p. 4090 - 4099
(2015/04/14)
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- Insights into the metalation of benzene and toluene by schlosser's base: A superbasic cluster comprising PhK, PhLi, and tBuOLi
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The metalation of benzene by Schlosser's base (nBuLi/tBuOK) occurs smoothly in THF at low temperatures to afford a discrete mixed-metal Li 2K4 cluster that contains phenyl anions and tert-butoxide. The aggregate itself exhibits superbasic behavior by metalating toluene. The delocalized benzyl anion obtained this way πbonds to potassium counterions, thereby creating a 2D coordination polymer. A discrete mixed-metal Li 2K4 cluster that contains phenyl anions and tert-butoxide is formed smoothly by the metalation of benzene by Schlosser's base (nBuLi/tBuOK) in THF at low temperatures (see picture). The aggregate itself exhibits superbasic behavior by metalating toluene. The delocalized benzyl anion obtained this way πbonds to potassium counterions, thereby creating a 2D coordination polymer.
- Unkelbach, Christian,O'Shea, Donal F.,Strohmann, Carsten
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p. 553 - 556
(2014/01/23)
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- Preparation of vinyl silyl ethers and disiloxanes via the silyl-heck reaction of silyl ditriflates
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Vinyl silyl ethers and disiloxanes can now be prepared from aryl-substituted alkenes and related substrates using a silyl-Heck reaction. The reaction employs a commercially available catalyst system and mild conditions. This work represents a highly practical means of accessing diverse classes of vinyl silyl ether substrates in an efficient and direct manner with complete regiomeric and geometric selectivity.
- Martin, Sara E. S.,Watson, Donald A.
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supporting information
p. 13330 - 13333
(2013/09/24)
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- Anomalous reactivity of silylborane: Transition-metal-free boryl substitution of aryl, alkenyl, and alkyl halides with silylborane/alkoxy base systems
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An unexpected borylation of organic halides with a silyborane in the presence of an alkoxy base has been observed. This formal nucleophilic boryl substitution can be applied to a broad range of substrates with high functional group compatibility. Even sterically hindered aryl bromides afforded the corresponding boryl compounds in high yields. Preliminary mechanistic studies indicated that this boryl substitution is promoted by neither transition-metal contamination nor a radical-mediated process.
- Yamamoto, Eiji,Izumi, Kiyotaka,Horita, Yuko,Ito, Hajime
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supporting information
p. 19997 - 20000
(2013/02/23)
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- A catalytic C-C bond-forming reaction between aliphatic fluorohydrocarbons and arylsilanes
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C-C coupling reactions between arylsilanes and alkylfluorides are efficiently catalyzed by disilyl cation 1. Primary as well as secondary alkylfluorides were quantitatively coupled with arylsilanes; however, in the case of tertiary fluorides, the hydrodef
- Luehmann, Nicole,Panisch, Robin,Mueller, Thomas
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experimental part
p. 533 - 537
(2010/10/19)
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- Formation of silicon-carbon bonds by photochemical irradiation of (η5-C5H5)Fe(CO)2SiR3 and (η5-C5H5)Fe(CO)2Me to Obtain R3SiMe
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Photochemical irradiation of an equimolar mixture of (η5 -C5H5)Fe(CO)2SiR3, FpSiR 3, and FpMe leads to the efficient formation of the silicon-carbon-coupled product R3SiMe, R3 = Me 3, Me2Ph, MePh2, Ph3, ClMe 2, Cl2Me, Cl3, Me2Ar (Ar = C 6H4-p-X, X = F, OMe, CF3, NMe2). Similar chemistry occurs with related germyl and stannyl complexes at slower rates, Si > Ge Sn. Substitution of an aryl hydrogen to form FpSiMe2C6H4-p-X has little effect on the rate of the reaction, whereas progressive substitution of methyl groups on silicon by Cl slows the process. Also, changing FpMe to FpCH2SiMe3 dramatically slows the reaction as does the use of (η5-C 5Me5)Fe(CO)2 derivatives. A mechanism involving the initial formation of the 16e intermediate (η5-C 5H5)Fe(CO)Me followed by oxidative addition of the Fe-Si bond accounts for the experimental results obtained.
- Fortier, Skye,Zhang, Yongqiang,Sharma, Hemant K.,Pannell, Keith H.
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experimental part
p. 1041 - 1044
(2010/04/25)
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- Generation and suppression of 3-/4-functionalized benzynes using zinc ate base (TMP-Zn-ate): New approaches to multisubstituted benzenes
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We present full details of our new methods for preparing functionalized benzynes with lithium di-alkyl(2,2,6,6-tetramethylpiperidino)zincate (R 2Zn(TMP)Li) through deprotonative zincation as a key reaction. In this system, by choosing appropriate ligands for the zincate, either regioselective zincation of functionalized haloaromatics or the generation of substituted benzynes can be controlled in good yields with excellent chemoselectivity, using the same substrate. Zincation with tBu 2Zn(TMP)Li followed by electrophilic trapping or zincation with Me2Zn(TMP)Li followed by nucleophilic or diene trapping is shown to be a powerful tool for the chemoselective preparation of 1,2,3-/1,2,4- trisubstituted benzene derivatives. These methods offer far greater generality than previous methods for the synthesis of multifunctionalized benzenes. Computational/theoretical studies of the reaction mechanism of this unique benzyne formation indicated that preferential coordination of the dialkylzinc moiety of zincate to halogen is the reason for the reduced activation energy of the elimination, that is, for the formation of the benzyne. The role of the ligands on Zn in accelerating/decelerating the elimination is also discussed.
- Uchiyama, Masanobu,Kobayashi, Yuri,Furuyama, Taniyuki,Nakamura, Shinji,Kajihara, Yumiko,Miyoshi, Tomoko,Sakamoto, Takao,Kondo, Yoshinori,Morokuma, Keiji
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p. 472 - 480
(2008/10/09)
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- From carbon dioxide to methane: Homogeneous reduction of carbon dioxide with hydrosilanes catalyzed by zirconium-borane complexes
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A mixture of a zirconium benzyl phenoxide complex and tris(pentafluorophenyl)borane is reported that catalyzes the hydrosilation reaction of carbon dioxide to generate methane via a bis(silyl)acetal intermediate. Copyright
- Matsuo, Tsukasa,Kawaguchi, Hiroyuki
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p. 12362 - 12363
(2007/10/03)
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- Reactions of dilithiobutadienes with monochlorosilanes: Observation of facile loss of organic groups from silicon
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Reactions of 1,4-dilithiobutadienes (from 1,4-diiodo-1,2,3,4- tetraethylbutadiene (1) and 2,2′-dibromobiphenyl (7) with t-BuLi) with Me3SiCl gave siloles (3 and 9a) as the major products. No evidence for a disilylated butadiene was obtained. Use of higher molecular weight chlorosilanes ((allyl)Me2SiCl, BnMe2SiCl, and PhMe 2SiCl) with dibromide 7 gave dimethylsilole 9a and a silane (10a, 10b, or 10c) resulting from trapping of the organic group by the chlorosilane.
- Hudrlik, Paul F.,Dai, Donghua,Hudrlik, Anne M.
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p. 1257 - 1264
(2007/10/03)
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- Intermolecular and intramolecular, platinum-catalyzed, acceptorless dehydrogenative coupling of hydrosilanes with aryl and aliphatic methyl C-H bonds
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Intermolecular acceptorless dehydrogenative coupling of silanes with arene C-H bonds and intramolecular coupling of silanes with aryl and alkyl C-H bonds occur in good yield in the presence of 5 mol % of TpMe2PtMe2H (Tpsu
- Tsukada, Naofumi,Hartwig, John F.
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p. 5022 - 5023
(2007/10/03)
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- Polymeric organosilicon systems. XXIX. Thermal properties of poly[(disilanylene)oligophenylenes]
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Thermal properties of variously substituted poly[(disilanylene)oligophenylenes], [(SiR1R2SiR1R2)(p-C6H4)m]n (R1=R2=Me, R1=R2=Et, and R1=Ph, R2=Me, m=1-4) were investigated. The thermogravimetric analysis of the polymers in the range of 20-1000°C showed rapid weight loss starting from about 400°C. The total weight loss of the polymers at 1000°C was calculated to be 54.5-75.5% based on the initial weight of the polymers. GC-MS analysis of the volatile products obtained from the pyrolysis of the polymers with R1=R2=Me, m=2 and R1=R2=Et, m=1-4 at 500°C indicated the formation of silicon-containing oligomers arising from the Si-Si and Si-phenylene bond cleavage, mainly. The formation of oligophenylenes, H(C6H4)lH (l=1-4), was also observed in the pyrolysis of the polymers with m=3 and 4. A model reaction for the polymer degradation was also examined, using 1,2-diphenyltetramethyldisilane.
- Ohshita, Joji,Sugimoto, Kazunori,Watanabe, Tsuguo,Kunai, Atsutaka,Ishikawa, Mitsuo,Aoyama, Susumu
-
-
- The preparation and analysis of the phenyldimethylsilyllithium reagent and its reaction with silyl enol ethers
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Phenyldimethylsilyllithium is formed from lithium and phenyldimethylsilyl chloride by slow cleavage of the Si-Si bond of 1,1,2,2-tetramethyl-1,2-diphenyldisilane after the rapid formation of the disilane. 1,1,2,2-Tetramethyl-1,2-diphenyldisiloxane, produced from the silyl chloride by reaction with oxides and hydroxides on the lithium metal surface, is cleaved by dimethyl(phenyl)silyllithium to give lithium dimethyl(phenyl)silanoxide. Dimethyl(phenyl)silyllithium reacts with 1,2-dibromoethane to give dimethyl(phenyl)silyl bromide, which is so rapidly consumed by excess silyllithium reagent that it does not interfere with the double titration used to measure its concentration. Dimethyl(phenyl)silane, produced by protonation of the silyllithium reagent, is also consumed by the silyllithium reagent to give 1,1,2,2-tetramethyl-1,2-diphenyldisilane, which regenerates the silyllithium reagent, as long as lithium is still present. By-products in the preparation of dimethyl(phenyl)silyllithium include 1,3-diphenyl-1,1,2,2,3,3-hexamethyltrisilane, dimethyldiphenylsilane and 1,4-bis[dimethyl(phenyl)-silyl]benzene. Dimethyl(phenyl)silyllithium displaces the silyl group from the tert-butyldimethylsilyl enol ether of cyclohexanone to give the lithium enolate under relatively mild conditions.
- Fleming, Ian,Roberts, Richard S.,Smith, Stephen C.
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p. 1209 - 1214
(2007/10/03)
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- Platinum Catalysed Regioselective ortho-Silylation of Benzylideneamines via Intramolecular C-H Activation
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The Pt-P(OCH2)3CEt complex catalyses the ortho-silylation of benzylideneamines with disilanes via intramolecular C-H activation; both mono- and bis-silylated products are obtained.
- Williams, Neil A.,Uchimaru, Yuko,Tanaka, Masato
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p. 1129 - 1130
(2007/10/02)
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- Cleavage of Si-C and Ge-C bonds in heterylsilanes and -germanes by organolithium reagents
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Organolithium reagents RLi can cleave Si-C and Ge-C bonds in heterylsilanes and -germanes substituting furyl, dihydrofuryl and dihydropyranyl groups for the organolithium residue R.
- Gevorgyan, Vladimir,Borisova, Larisa,Lukevics, Edmunds
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p. 381 - 387
(2007/10/02)
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- Photochemical reactions of aryl-substituted catenates of group 4B elements, PhMe2E-E'Me3 (E, E' = Si and Ge). Formation of a radical pair
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Photochemical reactions of phenyl substituted catenates of group 4B elements, PhMe2E-E'Me3 (E, E' = Si and Ge) have been investigated by chemical trapping experiments and laser flash-photolysis.On irradiation, the phenylated group 4B catenate undergoes E-E' bond homolysis to give a pair of radicals (PhMe2E. and Me3E'.).In CCl4, these radicals are converted to the corresponding chlorides by abstraction of a chlorine atom.In a nonhalogenated solvent, the radical pair couples at the ipso-position of the phenyl group of the pairing radical (PhMe2E.) to yield the cor responding diradical.This undergoes either elimination of a divalent species (Me2E:) with concomitant formation of trimethylphenyl group 4B element PhMe3E') or intramolecular 1,2-group 4B element migration to yield group 4B metal-carbon double bonded species.The radical escapes from the solvent cage coupled to the metal atom of the radical to yield the dimetallic product.The reaction path observed is highly dependent on the nature of the group 4B element comprising the phenyl substituted catenate.
- Mochida, Kunio,Kikkawa, Haruhiko,Nakadaira, Yasuhiro
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-
- Platinum Complex-catalysed Dehydrogenative Monosilylation of Alkenes with Disilanes
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Alkenes react with disilanes in the presence of platinum phosphine complex catalysts to give alk-1-enylsilanes.
- Hayashi, Teruyuki,Kawamoto, Aparecida M.,Kobayashi, Toshi-aki,Tanaka, Masato
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p. 563 - 564
(2007/10/02)
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- Uebergangsmetall-Silyl-Komplexe XXXIII. Einfluss der Substituenten am Silicium auf Stabilitaet und Zerfallsprodukte von Bissilyl-Komplexen des Palladiums, (R'3P)2Pd(SiR3)2
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Bissilyl complexes of PdII, (R'3P)2Pd(SiR3)2, are stable in the presence of electron-withdrawing silyl groups (e.g.SiCl3) or if the elimination of disilane is prevented by use of suitable chelate ligands.Reaction of cis-L2PdMe2 (L=MePh2P) with H2SiMePh or H2SiPh2 gives the complexes cis-L2Pd(SiHR2)2 (2) that are only detected spectroscpically; they decompose rapidly by cleavage of H2Si2R4.Reaction of L2PdMe2 with H2SiPh2 not only yields the bissilyl complex, but also HSiMePh2; with HSiPh3 only SiMe2Ph2, but no corresponding bissilyl complex is formed.In contrast, the distinctly more stable complex Pd(Ph2PCH2CH2SiMe2)2 is obtained by reaction of L2PdMe2 with Ph2PCH2CH2SiMe2H.Silanes containing chloro substituents (HSiCl3,HSiCl2Me, SiCl4) do not react with L2PdMe2 to give silyl complexes but undergo chloro/methyl exchange instead to give L2PdCl2 and methylated silanes.Trans-L2Pd(SiCl3)2 (4) was prepared by a novel route, viz., reaction of L2PdCl2 with HSiCl3 and KH.On thermolysis of 4 L2PdCl2 is formed in place of Si2Cl6.
- Schubert, Ulrich,Mueller, Christine
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p. 165 - 172
(2007/10/02)
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- Reactivity of cis-Bis(dimethylphenylsilyl)bis(phosphine)platinum Complexes toward Unsaturated Compounds Relevant to Double Silylation
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The reaction of phenylacetylene, tolane, or isoprene with cis-bis(dimethylphenylsilyl)bis(methyldiphenylphosphine)platinum readily took place to result in 1,2- or 1,4- double silylation, respectively.Ethylene also underwent double silylation with the platinum complex, but styrene selectively gave E-2-(dimethylphenylsilyl)styrene.
- Kobayashi, Toshi-aki,Hayashi, Teruyuki,Yamashita, Hiroshi,Tanaka, Masato
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p. 467 - 470
(2007/10/02)
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- Reductive Elimination of sym-Diphenyltetramethyldisilane from cis-Bis(phenyldimethylsilyl)bis(phosphine)platinum(II) Complexes
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Reductive elimination of cis-bis(phenyldimethylsilyl)bis(phosphine)platinum(II) complexes was found to occur to give sym-diphenyltetramethyldisilane together with redistribution by-products.Addition of free phosphine was favorable for the reductive elimin
- Kobayashi, Toshi-aki,Hayashi, Teruyuki,Yamashita, Hiroshi,Tanaka, Masato
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p. 1411 - 1414
(2007/10/02)
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- SIMPLIFIED APPROACH TO SILAANTHRONES AND DISILAANTHRACENES
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An improved synthesis of bis(o-chlorophenyl)methylsilane is reported from reaction of a mixture of o-BrC6H4Cl and MeSiHCl2 with Mg shavings in THF.The diarylsilanes, (o-ClC6H4)2SiMeR (R = H, Me) could be converted to diGrignard reagents with Mg prepared by the Rieke method but not from commercial Mg (shavings or mesh).The diorganomatallic reagents generated from (o-XC6H4)2SiMeR (R = H, Me) are used to prepare disilaanthracenes or silaanthrones.A new spiro derivative, bis(dimethyl-o,o'-diphenylsilyl)spirosilane, is obtained on addition of HSiCl3 to the diGrignard reagent generated from (o-ClC6H4)2SiMe2.When gaseous CO2 is added to the dilithio reagent formed from (o-BNrC6H4)2SiMe2, silaanthrone is produced which provides a new route to the silaanthracene framework.Aspects of this new ring closure route are described.
- Corey, J. Y.,McCarthy, W. Z.
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p. 319 - 326
(2007/10/02)
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- REACTION OF (BROMODIFLUOROMETHYL)PHENYLDIMETHYLSILANE WITH ORGANOMETALLIC REAGENTS
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A new fluorine-containing organosilicon compound, (bromodifluoromethyl)phenyldimethylsilane (II), was synthesized by the N-bromosuccinimide (NBS) bromination of (difluoromethyl)phenyldimethylsilane (I), which was prepared from phenyldimethylsilyllithium and chlorodifluoromethane.Compound II reacted with dimethyl sulfoxide to give dimethyl sulfide and phenyldimethylfluorosilane in quantitative yield.The reaction of II with nucleophiles, such as sodium ethoxide, Grignard or lithium reagents, afforded products arising from cleavage of the carbon-silicon bond.In contrast, the reaction of II with Grignard reagents in the presence of appropriate catalysts (Group VIII transition metal salts or complexes) afforded the homo-coupling product of II, 1,2-bis(phenyldimethylsilyl)-1,1,2,2-tetrafluoroethane (IV), in excellent yield.The silver(I) salt-catalyzed reaction of II with ethylmagnesium bromide gave the cross-coupling product, (1,1-difluoropropyl)phenyldimethylsilane (V) as well as III and IV.When cuprous bromide was employed as catalyst, the reaction of II with ethylmagnesium bromide afforded 1-phenyldimethylsilyl-1-propene (VI) and 3-phenyldimethylsilyl-2-pentene (VII) as main products.
- Fuchikami, Takamasa,Ojima, Iwao
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p. 145 - 153
(2007/10/02)
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